docs: def dinfFlowDirection(self,
                            flow_dir_grid,
                            slope_grid,
                            pit_filled_elevation_grid=None):
          """
          Calculates flow direction with Dinf method
          """
          log("PROCESS: DinfFlowDirection")
          if pit_filled_elevation_grid:
              self.pit_filled_elevation_grid = pit_filled_elevation_grid
  
          # Construct the taudem command line.
          cmd = [os.path.join(self.taudem_exe_path, 'dinfflowdir'),
                 '-fel', self.pit_filled_elevation_grid,
                 '-ang', flow_dir_grid,
                 '-slp', slope_grid,
                 ]
  
          self._run_mpi_cmd(cmd)
  
          # create projection files
          self._add_prj_file(self.pit_filled_elevation_grid,
                             flow_dir_grid)
          self._add_prj_file(self.pit_filled_elevation_grid,
                             slope_grid)